CHANULXCAT ivo://nasa.heasarc/chanulxcat NASA/GSFC HEASARC Swartz et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source One hundred fifty-five (the abstract in the paper erroneously states the number to be 154) discrete, non-nuclear, ultraluminous X-ray (ULX) sources, with spectroscopically determined intrinsic X-ray luminosities greater than 10<sup>39</sup> erg/s, have been identified in 82 galaxies that were observed with Chandra's Advanced CCD Imaging Spectrometer (ACIS). Positions, X-ray luminosities, and spectral and timing characteristics of these ULXs are contained in this table. Eighty-three percent of ULX candidates have spectra that can be described as absorbed power laws with mean index Gamma = 1.74 and column density N<sub>H</sub> = 2.24 x 10<sup>21</sup> atoms cm<sup>-2</sup>, or ~5 times the average Galactic column. About 20% of the ULXs have much steeper indices indicative of a soft, and likely thermal, spectrum. The locations of ULXs in their host galaxies are strongly peaked toward their galaxy centers. The deprojected radial distribution of the ULX candidates is somewhat steeper than an exponential disk, indistinguishable from that of the weaker sources. About 5%-15% of ULX candidates are variable during the Chandra observations (which average 39.5 ks). Comparison of the cumulative X-ray luminosity functions of the ULXs to Chandra Deep Field results suggests ~25% of the sources may be background objects, including 14% of the ULX candidates in the sample of spiral galaxies and 44% of those in elliptical galaxies, implying the elliptical galaxy ULX population is severely compromised by background active galactic nuclei. Correlations with host galaxy properties confirm the number and total X-ray luminosity of the ULXs are associated with recent star formation and with galaxy merging and interactions. The preponderance of ULXs in star-forming galaxies as well as their similarities to less-luminous sources suggest they originate in a young but short-lived population such as the high-mass X-ray binaries, with a smaller contribution (based on spectral slope) from recent supernovae. The number of ULXs in elliptical galaxies scales with host galaxy mass and can be explained most simply as the high-luminosity end of the low-mass X-ray binary population. This table was created by the HEASARC in March 2007 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/154/519">CDS catalog J/ApJS/154/519</a> file table2.dat. This is a service provided by NASA HEASARC . 2004ApJS..154..519S https://heasarc.gsfc.nasa.gov/W3Browse/all/chanulxcat.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=chanulxcat& GET text/xml 180 99999 true 213.223 -65.38186111 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=chanulxcat GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_chanulxcat&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 X-ray public chanulxcat Chandra Archive Of Galaxies Ultraluminous X-Ray Source Catalog galaxy_name Galaxy Designation char nullable name Catalog Designation ([SGT2004] JHHMMSS.SS+DDMMSS.S) meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable lx Intrinsic Luminosity (erg/s) erg/s double nullable lx_error Uncertainty in Intrinsic Luminosity (erg/s) erg/s double nullable lx_flag Flag [d] Indicates Intrinsic Luminosity from Fit of Thermal Emission-Line Model char nullable hardness_ratio_2 Hardness Ratio of (1.0-2.0keV)-(0.5-1.0keV) Relative to Total Counts phot.flux;arith.ratio;em.X-ray.soft double nullable chi_squared Chi Squared of Model Fit double nullable lx_obs Observed Luminosity (erg/s) erg/s double nullable spect_shape_neg_err Lower Limit Error on Power-Law Index double nullable spect_shape_flag Flag [bc] Indicates Type of Model: b=Disk-Blackbody, c=Thermal Emission-Line char nullable nh_neg_err Lower Limit Error on Hydrogen Column Density (H-atoms/cm^2) H-atoms/cm^2 stat.error;phys.columnDensity double nullable prob_constant Kolmogorov-Smirnov Significance That Source Deviates from Steady Source double nullable bii Galactic Latitude degree pos.galactic.lat double nullable lx_obs_error Uncertainty in Observed Luminosity (erg/s) erg/s double nullable dof Model Degrees of Freedom short nullable lii Galactic Longitude degree pos.galactic.lon double nullable nh_pos_err Upper Limit Error on Hydrogen Column Density (H-atoms/cm^2) H-atoms/cm^2 stat.error;phys.columnDensity double nullable hardness_ratio_1 Hardness Ratio of (2.0-8.0keV)-(1.0-2.0keV) Relative to Total Counts phot.flux;arith.ratio;em.X-ray.medium;em.X-ray.soft double nullable spect_shape Power-Law Index double nullable spect_shape_pos_err Upper Limit Error on Power-Law Index double nullable nh Hydrogen Column Density (H-atoms/cm^2) H-atoms/cm^2 phys.columnDensity double nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable